Generally, a sequence program is created by graphically arranging constituent elements of a program on an editor screen by using a program editor. Particularly, a ladder program, which is one of such sequence programs, is configured by circuit blocks. The circuit blocks are created by arranging circuit elements (such as contacts, coils, commands, and functional blocks) as the constituent elements thereof on the editor screen of the program editor.
At the time of editing a ladder program by a program editor, upon specification of a search key, a similar part search is selected from a menu, and then program parts similar to the search key can be displayed on a search display screen. As a user selects an intended program part from the displayed search results and drags and drops the selected program part on an editor screen, the program parts are arranged on the ladder program.
Patent Literature 1 discloses a technique in which a circuit satisfying conditions and all circuit elements specified in the same circuit is identified and the identified circuit is displayed.